Kyle White

Irwin was leading Peter Hickman in the race by 1.1 seconds when the red flag came out following a serious crash at the end of lap six.

With the rider involved lying stricken on the track, the race was immediately stopped. Sadly, it was later confirmed that the competitor involved - Dan Hegarty (31) from Nottingham - had been killed in the incident.

Carrick man Irwin, who appeared visibly upset as he made his way onto the podium in a subdued atmosphere afterwards, said on Twitter: "Thanks for all messages. Tough race, fault with bike from beginning made it hard but absolutely irrelevant. My thoughts are with the rider."

PBM Ducati rider Irwin took the lead of the race off the line from pole on the Panigale, but two-time winner Hickman hit the front with a move on the brakes into Lisboa.

However, Irwin had nosed ahead again by the end of the lap and was attempting to break the tow of his SMT Bathams BMW rival.

The leading duo quickly began to pull clear of Martin Jessopp in third on the Riders Motorcycles BMW, who was being chased by eight-time winner Michael Rutter (SMT Bathams BMW) and Conor Cummins on the Padgetts Honda.

Irwin had opened a visible lead over Hickman by lap four, but the English rider slashed the deficit on lap five as the race began to build into a straight shootout between the fellow British Superbike men.

There was only 1.1 seconds between the pair when the race was stopped, with Rutter out of contention in third, some seven seconds in arrears.

Irwin is the first rider from Northern Ireland since Phillip McCallen in 1996 to win the race.

Yeovil man Jessopp was confirmed in fourth place ahead of Cummins, with Gary Johnson completing the top six on the Briggs Kawasaki.